forgot the 7mm rum

Thanks for your help, but i forgot to include the 7mm rum. Where does this stack up to the other calibers, and do you think I will have trouble finding ammo for it in the future. Also what kind of scope would you need to make a 1000 yard shot? I dont mean to sound dumb, but i never shot an animal over 300 yards. I am open to any suggestions. This site and you guys are great, thanks!!